Media data recorders are widely used in individual and industrial businesses such as exchange of letters and documents, performing document scanning, printing, copying or facsimile operations. There is a wide variety of media data recorders, such as ink-jets, lasers and impact printers, plotters, scanners, copiers, multi-functional peripheral (MFP), and the like. Printing quality and operation efficiency of the media data recorders have always been key development focuses in this industry.
The present media data recorders, such as copiers, mostly employ roller mechanisms to convey media in the operations of media feeding, scanning, printing or discharging. FIGS. 1A and 1B illustrate the general or conventional technique of the media conveying mechanism that is usually adopted. It mainly includes a pickup roller 110, intermediate roller 120 and delivery roller 130. A motor 100 provides the driving power required for roller operation. In practice, there are also belts or a plurality of auxiliary gears to couple with the main operation gears and motor 100. The drawings show only three main operation gears. When a copier media (such as paper 200) is fed, the pickup roller 110 and the intermediate roller 120 rotate counterclockwise at the same time to pick up the paper 200. Meanwhile, the delivery roller 130 rotates clockwise aiming to align the front edge of the paper 200 before it arrives at the delivery roller 130 so that the paper 200 can pass through an image processing device 140 and obtain correct image output without skewing. As shown in FIG. 1B, after the paper 200 has been aligned, the delivery roller 130 transports the paper 200 for discharging with the aid of the rotating intermediate roller 120.
The operation of the conventional mechanism set forth above requires a motor 100 to switch rotation clockwise or counterclockwise. And only when the paper 200 has been completely moved away from the delivery roller 130 can the motor 100 switch operation direction to pick up the next paper 200. Hence two consecutive papers 200 have to be spaced from each other for a long distance. This causes unnecessary idling of the image-processing device 140 or other printing conveying modules. This is not efficient.